| Four cassava varieties, Kasetsart 50, Huay Bong 60, Rayong 9 and Rayong 72 were observed for mealybug in a survey that was conducted in Kalasin Province, Khon Kaen province and Udon Thani Province from November 2011 to September 2012. The infestation of pink mealybug was counted in five levels, 0 level 0 mealybug, 1st level (1-9), 2nd level (10-99), 3rd level (100-999) and 4th level (≥1,000). On the other hand, leaf curl level was categorized into five scores as follows; margin declined slightly was categorized at normal was categorized at level 0, margin declined slightly at level 1, shoot stunted at level 2, shoot distorted at level 3 and leaves fall at level 4. Rayong 72 variety showed the highest population of mealybug at 25.5% (MbL1) and 22.5 % (MbL2)... |
